A.D. 1558.—Porta (Giambattista della), Italian natural philosopher (1540–1615), carries on a series of experiments with the magnet for the purpose of communicating intelligence at a distance. Of these experiments, he gives a full account in his “Magiæ Naturalis,” the first edition of which is said to have been published at Naples when Porta was but fifteen years of age (“Encycl. Brit.,” article “Optics”). Prof. Stanley Jones says this is the earliest work in which he has found allusions to a magnetic telegraph.
Porta’s observations are so extraordinary—and they attracted so much attention as to justify eighteen separate editions of his work in different languages prior to the year 1600—that extracts must needs here prove interesting. They are taken out of “Natural Magick in XX Bookes by John Baptist Porta, a Neapolitaine ... London 1658,” the seventh book of which treats “Of the wonders of the loadstone.”
Proem: “And to a friend that is at a far distance from us and fast shut up in prison, we may relate our minds; which I doubt not may be done by two mariner’s compasses, having the alphabet writ about them ...”
Chap. I (alluding to the loadstone):
“The Greeks do call it Magnes from the place,
For that the Magnet’s hand it doth embrace.”
Nicander thinks the stone was so called—and so doth Pliny—from one Magnes, a shepherd.
In Chap. XVIII he states that “the situation makes the Vertues of the Stone contrary ... for the stone put above the table will do one thing, and another thing if it be put under the table ... that part that drew above will drive off beneath; and that will draw beneath that drove off above: that is, if you place the stone above and beneath in a perpendicular.”
In Chap. XXV, in allusion to “a long concatenation of iron rings,” he thus quotes Lucretius:
“A stone there is that men admire much